package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.pojo.Blog;
import com.hmdp.pojo.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 王艺锡
 * @since 2024-04-26
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //使用工具类中的方法解决缓存穿透问题
       /* Shop shop = cacheClient
                .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        */

        //使用互斥锁解决缓存击穿
        // Shop shop = queryWithMutex(id);

        //使用逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicExpire(id);

        //使用工具类中的逻辑过期解决缓存击穿
        Shop shop = cacheClient
                .queryWithLogicExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L, TimeUnit.SECONDS);
        if (shop == null) {
            return Result.fail("店铺不存在!");
        }
        return Result.ok(shop);
    }

    /*//设置一个线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    //解决缓存穿透和缓存击穿的问题(使用逻辑过期)
    public Shop queryWithLogicExpire(Long id){
        //redis中存储商铺信息的key
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isBlank(shopJson)){
            //3.不存在，返回空
            return null;
        }

        //4.不为空，先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject jsonObjecte = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(jsonObjecte, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断数据是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            //5.1.如果未过期，直接返回店铺信息
            return shop;
        }
        //5.2.如果过期了，需要进行缓存重建
        //6.缓存重建
        //6.1.获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean flag = getLock(lockKey);
        //6.2.获取成功，开启独立线程，重建数据
        if(flag){
            //先对缓存进行二次查询
            shopJson = stringRedisTemplate.opsForValue().get(key);
            redisData = JSONUtil.toBean(shopJson, RedisData.class);
            jsonObjecte = (JSONObject) redisData.getData();
            shop = JSONUtil.toBean(jsonObjecte, Shop.class);
            expireTime = redisData.getExpireTime();
            //如果未过期
            if(expireTime.isAfter(LocalDateTime.now())){
                return shop;
            }

            //如果过期了，开启独立线程，重建数据
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {

                    this.saveShopToRedis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //删除互斥锁
                    deleteLock(lockKey);
                }
            });
        }

        //6.3.先返回过期的商铺信息
        return shop;
    }



    //解决缓存穿透和缓存击穿的问题(使用互斥锁)
    public Shop queryWithMutex(Long id){
        //redis中存储商铺信息的key
        String key = CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if(StrUtil.isNotBlank(shopJson)){
            //3.存在，返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //如果命中的是空串
        if("".equals(shopJson)){
            return null;
        }

        //4.不存在，获取锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean flag = getLock(lockKey);
            //4.1.获取失败，休眠，重新查询
            if(!flag){
                Thread.sleep(50);
                return queryWithMutex(id);
            }

            //5.拿到锁，再次查询缓存
            shopJson = stringRedisTemplate.opsForValue().get(key);
            //5.1查询到了，返回
            if(StrUtil.isNotBlank(shopJson)){
                shop = JSONUtil.toBean(shopJson, Shop.class);
                return shop;
            }
            //如果命中的是空串
            if("".equals(shopJson)){
                return null;
            }

            //6. 查询不到，根据id查询数据库
            shop = getById(id);
            //7.不存在，返回错误信息，将空值写入redis
            if(shop == null){
                //将空值写入redis-->解决缓存穿透的问题
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }

            //8.存在，把数据写入redis中
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //9.释放互斥锁
            deleteLock(lockKey);
        }

        //10.返回
        return shop;
    }
    */

    public void saveShopToRedis(Long id, Long expireSeconds) throws InterruptedException {
        //1.根据id查询商铺信息
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.存入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }
/*
    //获取锁
    private boolean getLock(String key){
        //setnx,有效期为10s
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    //删除锁
    private void deleteLock(String key){
        stringRedisTemplate.delete(key);
    }*/

    @Override
    @Transactional
    public Result update(Shop shop) {
        //1.判断商铺id是否存在
        if (shop.getId() == null) {
            Result.fail("商铺id不能为空!");
        }
        //2.更新数据库
        updateById(shop);
        //3.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();
    }

    /**
     * 查询附近商铺
     * @param typeId
     * @param current
     * @param x
     * @param y
     * @return
     */
    @Override
    public Result queryByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }

        //2.计算分页所需参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        String key = SHOP_GEO_KEY + typeId;
        //3.查询redis，按照距离进行分页和排序，结果：shopId，distance
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        //4.解析id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            //没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        //4.1.截取from-end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> map = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            //4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3.获取距离
            Distance distance = result.getDistance();
            map.put(shopIdStr,distance);

        });
        //5.查询数据库
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(map.get(shop.getId().toString()).getValue());
        }
        //6.返回数据
        return Result.ok(shops);
    }



}
